Volume 5 Issue 5
Chris Benedict, WSU Whatcom County Extension
Undoubtedly the conversations about this spring weather has been how warm it has been. Spring of 2015 progressed at a very fast clip and 2016 has looked very similar so we wanted to look back over the past four months. Below are just a few highlights; all information was derived from WSU AgWeatherNet.
Looking back at the winter of 2015-2016 one resounding fact sticks out. The last frost date at two of four County stations was the middle of January (1/15). Comparing this to years 2008-2015 this was much earlier in the calender year. Also, the number of frost-free days are considerably more the past few years when compared to even nine years ago. This may not be part of a longer term trend, but is something that inevitably is having an impact on pests and perennial plant development.
Growing Degree Days
Growing degree days gives you the ability to look at the accumulation of heat over a given time. If we compare 2016 to the seven year average between 2009 and 2015 the two data sets really start to separate in early April (blue arrow). It should be noted that for some sites (Lawrence and Lynden) differences to seven year average started as early as mid March. This last fact underscores the influence of micro-climates.